Can the hourly backups by Time Machine be stopped? I'm on Lion and if it matters, each hour it tries to backup about 30GB (I don't know where this 30GB comes from, as today I've only modified a few text files and browsed the web). This results in the computer slowing down noticeable and beachballing more often.

Or even better than stopping them completely change the hourlys to every 2-4 hours?

It is backing up to a TimeCapsule, so I think the network might be the reason it is slowing down noticeable, that and it's a late 2008 MacBook Pro.

TimeMachineEditor is a software for Mac OS X Leopard, Snow Leopard and
Lion that lets you change the default one-hour backup interval of Time
Machine. You can change the interval or create a more sophisticated
scheduling (see screenshot below). This is useful if you don’t need
to backup every hour and don’t want the performance penalty. This is
also especially useful if you manipulate lots of data within one hour
as you would spend the whole day backing up.

Changing your interval should not affect the daily or monthly backups, which are not actually any different to the hourly ones in any material way.

To get a better idea of what is causing large or lengthy backups, you can use the Backup Loupe software, available for free download at:

"With BackupLoupe you are able to answer questions like Why is Time
Machine so slow? Why is my Time Machine drive already full? Which
files are actually being backed up? Has a particular file/folder been
backed up at all? How many revisions of a file/folder exist in Time
Machine? A file/folder was deleted accidentally. When did this happen
and where is the latest backup? Is my backup drive big enough? Should
I consider buying a larger one? And if yes, when?"

Wow! Why is this not included by default. Thank you.
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Jonathan.Mar 17 '12 at 21:10

1

I looove this tool. My time capsule is quite loud during backups. This tool comes in quite handy when reducing the amount of backups.
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gentmattMar 17 '12 at 21:11

If I set the time interval to 3 hours, will it still do the monthly and daily backups (and keep them for the lengths of time as described in Time Machine preferences)?
–
Jonathan.Mar 30 '12 at 19:20

@Jonathan. It will still perform the backups and keeps them for as long as the storage is enough. What you are talking about is locked documents which is a feature related to versions.
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gentmattMar 30 '12 at 19:22